Circuit interrupter



F 16, 7- E. F. BECK 2,071,158

CIRCUIT INTERRUPTBR Filed Aug. 25, 1933 fliyi. III

as /3- I Edwam F Beck ATTORN Patented Feb. 16, 1937 UNITED STATES PATENT OFFICE Westinghouse Electric a Manufacturing Company, last Pittsburgh, Pa, a corporation of Pennsylvania Application August 25, 1933, Serial No. 685.765

29 Claims.

My invention relates to circuit interrupters and particularly to cutout devices for protecting equipment such as distribution transformers.

Protective equipment for apparatus of this type is required to perform two main functions: First, it should reliably and positively interrupt the controlled circuit upon the occurrence of predetermined overload conditions. regardless of the magnitude of the overload. And, second, it

should in some manner readily indicate to a maintenance operator that the cutout has functioned. this last being especially important when the devices areused to protect pole mounted transformers or the like, because it is desirable that the i5 operator be able to ascertain whether a cutout has functioned without having to climb the pole. In addition to the above functional requirements, a satisfactory device of this type should be easy to install and must be relatively inexpensive, due

to the large numbers which are used on even a moderate size distribution system.

It is an object of my invention. therefore, to provide an improved electrical cutout that shall be simple in design. reliable in operation, and ina expensive to manufacture, and that shall be capable of readily indicating when it has operated to open the controlled circuits.

It is also an object of my invention to provide an improved cutout that shall be entirely mountable upon one of the line conductors of a transmission system, and that shall include means for producing an expulsive blast of cut-flowing gas for extinguishing the arc during the circuit interrupting operation. a

A further object of my invention is to provide a novel heating means for causing the operation of thermally responsive devices, my novel heating means to include an electro-responsive device forcontrolling the heating eifect thereof in accord- 40 ance with circuit conditions.

A further object of my invention is to provide an improved circuit interrupting device that shall include a frangible closure, and electro-responsive means within the frangible closure for creat- 45 ing pressure to effect the opening ofthe controlled circuit.

A still further object of myinvention is to provide a novel circuit interrupter, having movable contact means biased to the open circuit position no and an improved electro-responsive means for.

holding the interrupter closed against the action of the biasing means.

These and other objects of my invention will 55 be more clearly understood from the io w s de- (CL "(F-123) scription of a preferred embodiment of my invention.

Referring to the drawing:

Figure 1 is an elevational view of a cutout embodying the principal features of my invention. 5 Fig. 2 is a sectional view of the cutout shown in Pig. 1, on the line II--1I of that figure. l ll igz. Sisasectional viewonthelineIlI-lIlcf g. Fig.4isasectionalflewonlineIV-Ncfm Pig. 2.

Fig. 5 is a detail view'showing the conducting member disposed in the lower portion of the cutout shown in Figs. 1 to 4.

Fig.6isasectionalvlewonthelineVI-Vlcf 15 Pig. 5.

Fi s. '1 and 8 are detail views showingthe conducting plate which cooperates with the member shown in Figs. 5 and 6. and

Fig. 9 is a fragmentary perspective view showing two of the cutouts illustrated in Figs. 1 to 4 in use with a distribution transformer.

as shown in the drawing, the preferred embodiment of my invention comprises a metallic cap member Landaporcelaininsulatingmembert havingatubularpassagelthereinfor containing the other elements of the device. lbs percelain insulating member 8 is cemented to the cap member I by. means of suitable cementing material'l. Anannuiarwasherlofeorkorlikematerial isinterposedbetweentheupmedgescftbe insulating member 3 and the cap member i in order to make a gas tight connection and to prevent unduestrainbeingplacedon theinsulating member during the cementing process. line can member i is provided with an up-standing portion ll formed integral therewith. This portion ll hasathreadedopening II and two II and I1 machined therein. and is adapted to cooperate with a clamp member II to permit the devicetobeconnectedtooneoftheconductorscf aline. Theboltil andthelock washer it provide a convenient means for readily connecting and disconnecting the cap member I from the line conductor.

The lower portion of the tubular passage I is partially closed by an annular shoulder II; which is formed integral with the insulating member 8. This annular shoulder 25 serves as a retaining means for holding theelectro-respono sive heating means used in this embodiment of" my invention within the e 8. In addition, it provides a convenient means for restricting the area of the opening through which the gases formed within the device during the circuit inst terrupting operation are vented thereby increasing the arc extinguishing capacity of the device.

One end of the flexible conductor 21, which is used for completing the electrical circuit from the interrupter to the controlled apparatus, is soldered in the recess 3| provided in the conducting member 29 (shown particularly in Figs. 5 and 6). The conducting member 29 is adapted to be supported in the central opening 33 in the annular portion 25 of the insulating member 3 by means of a fusible alloy 35 disposed therein. The edge portion 31 of the conducting member 29 cooperates with the alloy 35 and the annular portion 25 of the insulating member to effectively seal the tubular passage 5 within the cutout,

thereby forming a closed gas-tight chamber.

A metal plate 39 having a dished portion 3! and a centrally disposed opening 43 (Figs. 7 and 8) is positioned immediately above the annular base portion 25 of the insulating member 3. Immediately above this plate are three conducting plates 45 (Fig. 4), which are preferably of a non-metallic resistance material such as carbon or a solid agglomerate consisting chiefly of silicon carbide. A circular metal plate 41 is disposed above the three non-metallic resistance plates 35, and is electrically connected to the cap member I by means of a flexible shunt 49, one end of which is brazed or otherwise conductively joined to each of the two connected members. A fusible link 5| is conductively Joined to the upper metal plate 41 and the lower metal plate 39, and serves to provide a conducting path through the cutout which is electrically in parallel with the conducting path provided by the three resistance disks 35.

A high temperature solder is used for fastening the end of the flexible conductor 21 to the conducting member 29. For holding the conducting member 29 in the passage 33 within the lower portion of the insulating member 3 and for completing the electrical circuit from the conducting member 29 to the lower plate 39, I prefer to use a low temperature lead-tin alloy, the proportions of which closely approximate the proportions of the eutectic alloy of those metals. These alloys have very sharp melting points, usually in the neighborhood ofto C. and permit very accurate calibration of any thermally responsive device wherein they are used.

The remainder of the tubular passage 5 within the porcelain insulating member 3 is preferably filled with a halogenated wax 39 having a melting point somewhere in the neighborhood of 100 C. These waxes are readily vaporizable upon the application of heat to form large quantitles of gas which, when properly directed, may be utilized for extinguishing an electric arc, and at the same time, when the waxes are cold they have considerable mechanical strength, thereby serving to securely hold the various parts of the device within the tubular space 5.

The electrical circuit through the cutout is comparatively direct: Beginning with the upstanding portion II, which is adapted to be conductively joined to one'of the conductors of a transmission line by the clamp member IS, the current flows successively through the cap I itself, the flexible conducting member 39 disposed within the tubular insulating member 3, thence through the parallel path formed by the three flat disks 45 of resistance material and the fusible element 5| to the lower conducting p a e 39,. a d

finally through the fusible alloy 35 intermediate the lower conducting member 39 and the conducting member 29 to the flexible conductor 21. The flexible shunt 49 is of suflicient length that the various parts of the device may be entirely assembled within the insulating member 3, the wax l8 poured in, and the upper end of the shunt 39 then connected to the inside of the cap member i; the remaining steps being the placing of the insulating member 3 within the cap I and the pouring in of the cement I.

It will be noted, as shown particularly in Fig. 4, that the porcelain insulating member 3 is provided with a section 53 of restricted cross sectional area disposed immediately adjacent the lower resistance disk 45. This section 53, as will be explained later, permits the insulating member 3 to be broken when the pressure within the device reaches a predetermined point, and also serves to permit the insulating member to be broken by local heating, to cause the interrupter to open the controlled circuit.

The weight of the flexible conducting member 21, which is used for connecting the cutout to the controlled apparatus, is depended upon to provide a biasing force tending to separate the conducting means which are mounted on either end of the tubular insulating member 3, that is, the cap I' and the conducting member 29.

The operation of my invention is substantially as follows: Upon the occurrence of a moderate overload which is of just sufficient magnitude to cause the fusing of the fusible element 5! connected in parallel with the three resistance disks 45 all of the current carried by the device must flow through these disks and thereby generate heat. The immediate result is to heat the lower conducting plate 39 and if the overload continues for a sufllcient period of time, it will ultimately result in the fusion of the low temperature alloy 35 intermediate the conducting plate 39 and the conducting member 29 fastened to theflexible conductor 21. The fusing of the alloy 35 will then permit the biasing effect of the weight of the flexible conductor 21 to move the conducting member 29 out of the opening 33 within the lower end of the insulating member 3, thereby opening the circuit. Since the 'flexlbleconductor completely disengages the cutout during the circuit interrupting operation, a maintenance operator standing on the ground may readily ascertain that the device has operated without having to climb the pole or other supporting structure.

Upon the occurrence of a somewhat larger overload which is capable of causing veryrapid fusion of the fusible link 5|, one of two things may take place. Either the low temperature fusible alloy 35 intermediate the lower conducting plate and the conducting member 29 fastened to the flexible conductor 21 will melt, thereby permitting the circuit to be opened by the falling of the flexible member, as described above, or suffi: cient local heating of the reduced area section 53 of the porcelain insulating member 3 will result to cause that member to break, thereby permitting the entire end portion of the insulating member to fall, thereby opening the circuit. This breaking of the porcelain member 3 results from the fact that porcelain has a sufllciently high coemcient of thermal expansion that localized heating if brought about with suflicient rapidity, will invariably cause the' porcelain to break.

Upon the occurrence 01 very heavy overloads or short circuit conditions in the protected appara- 1B tus, the fusible link II will melt practically instantaneously. The fusing of this member will probably result in the formation of an are which isoftoolargeamagnitudetobeentirelyextinguisbed due to the conducting path in parallel therewith (the three resistance disks 4|). Thus.

while a considerable portion of the overload current will flow through the resistance disks It, therewiilbean arcwithinthetubularpassage formed by the. walls of the insulating member 8.

'ihisarcwillactuponthehalogenatedwaxllor other compound'which is disposed therein and will cause immediate volatiliaation of a considerable quantity of that wax or other compound. If

this volatilisation proceeds at a sufliciently rapid rate, the pressure within the chamber formed by the insulating member 3 and the cap member I will cause the insulating member to break adiacentthesectionlsofredueedcrosssectional area, thereby causing the entire lower portion of thetubularinsulatingmemberstobeexpelled from the remainder of the device with considerable force. The out-flowing blast of gas from the interior of the cutout, which will follow the rupture of the frangible closure 3, will materially aid 'inextinguishingthearcandtherebyinterrupting 8|. and. due to the high velocity which results from the pressure within the device. will cause a practically immediate extinction of any are which might be formed due to the separation of the conducting member I. and the lower conducting P te II.

No vent passage is provided for causing the gas formed during the interruption of heavy current overloads to vent through the central. opening 38 in the lower portion of the insulatingmembersandtheopeningllintheconducting plate II, the normal manufacturing inaccuracies of these parts being sumcient 'to permit the gas to raise up the resistance plates 4! and flow therebetween.

Itshould also be noted that some gas will be evolvediromthewaxflduringeachcperationof the cutout, due to the heating effect of the re- 'sistance discs ll, but it is only upon the occurrence of moderate and large overloads that large gas v are developed within the device. As a result, the velocity and the volume of the outflowing arc extinguishing gases are greatest when the cutout is required to open large overloads.

It will thus be s'eenthat I have disclosed a novel form of circuit interrupter of the cutout type which is particularly suitable for use in protecting distribution transformers or other appsratus which may be mounted in an inaccessible place. My improved cutout includes means visible at a considerable distance for indicating when the circuit has been opened due to operation of the device; it is simple in design. inexpensive to manufacture and may be installed in a short period of time with a minimum of effort. Moreover, my improved circuit interrupting device is entirelympportedupononeoftheconductorsof the transmission line, thereby eliminating the necessity for any intermediate supportmeans.

Further, I have disclosed a novel form of circuit interrupter which utilizes an expulsive blast of arc extinguishing gas for interrupting a circuit, my novel circuit interrupter being provided with a frangible closure and means whereby the closure may be broken during the operation of the device to effect the interruption of the controlled circuit. In effecting these novel results, I have utilized an improved thermally-responsive heat ing element which is applicable to electrical apparatus generally.

While in accordance with the patent statutes, I have disclosed the details of a preferred embodiment of my invention, it is to be understood that many of these details are merely illustrative and variations in their precise form will be both possible and necessary in some applications. I desire, therefore, that my invention be limited only asset forth in the appended claims and by the prior art.

I claim as my invention:

1. In a circuit interrupter, means movable from a closed circuit position to an open circuit position to open the circuit, means biasing said movable means toward the open circuit position, current-carrying heater means, means responsive" to the heating effect of said-heater means for normally preventing said biasing means from causing said movable means tomove from the closed circuit position to the open circuit position, and

current-carrying electro-responsive means normally connected in parallel with said heater means for limiting the current flow in said heater means until the occurrence of predetermined conditions in the circuit controlled by said interrupter.

2. In a circuit interrupter, means biasing said interrupter to the open circuit position, a current carrying heater means. means which normally prevents said biasing means from actuating said interrupter but which is operable in response tb the heat produced by said heater means to allow said biasing means to cause said interrupter to move from the closed circuit position to the open circuit position,-and a fusible element connected in parallel with said heater means. said element fusing upon the occurrence of predetermined conditions'to cause an increase in the heating effect of said heater means.

3. In a circuit interrupter, means movable from a closed circuit position to an open circuit position to open the circuit, means biasing said movable means to the open circuit position, fusible means for retaining said movable means in the closed circuit position against said biasing means. and current carrying heater means for causing said fusible means to release said movable means. thereby effecting the opening of the circuit controlled by said interrupter, said heater means comprising a resistance unit and a fusible element electrically connected in parallel.

4. In a circuit interrupter, means movable from a closed circuit position to an open circuit position to open the circuit, means biasing said movable means to the open circuit position, thermally responsive means for retaining said movable means in the closed circuit position against said biasing means, and current carrying heater means, comprising at least one substantially flat plate of non-metallic material thermally conductively Joined to -said thermally responsive means for causing said interrupter to move to the open circuit position uopn the occurrence of predetermined conditions.

5. In a circuit interrupter, means movable from a closed circuit position to an open circuit position to open the electrical circuit through said interrupter, means biasing said movable means to the open circuit position, thermally responsive means comprising a means of fusible material for retaining said movable means in the closed circuit position against said biasing means, and ourrent-carrying heater means, comprising at least one flat plate of non-metallic resistance material thermally conductively joined to said means of fusible material, for causing said interrupter to move to the open circuit position upon the occurrence of predetermined conditions.

6. In a circuit interrupter, a tubular means of insulating material having terminal means at either end and a section of reduced cross section intermediate said terminal means, said tubular means and said terminal means forming a substantially closed chamber, heat responsive means within said chamber for creating pressure therein, and heater means forv said heat responsive means, comprising an electro-responsive element, operable upon the occurrence of predetermined conditions to cause suillcient pressure within said chamber to rupture said tube adjacent said section of reduced area and thereby open the circuit controlled by said interrupter.

7. In a circuit interrupter, means defining a chamber, at least a portion of the walls of'which comprise insulating material having a sufllciently large coefllcient of thermal expansion that local heating will cause said insulating material to break, and heater means positioned within said chamber adjacent said breakable portion and comprising an electro-responsive element operable upon the occurrence of predetermined conditions to cause sufllcient local heating adjacent said portion to effect the breaking of said wall portion and thereby cause the opening of the circuit controlled by said interrupter.

8. In a circuit interrupter, a tubular means of insulating material having a sufllciently large coemcient of thermal expansion that local heating will cause said insulating material to break, metallic conducting means supported at either end of said tubular means, means biasing at least one of said conducting means away from the.

other of said conducting means, and heater means disposed within said tubular means and comprising an electro-responsive element operable upon the occurrence of predetermined conditions to cause sufflcient local heating of a portion of said tubular means which is located intermediate said conducting means to break said I means comprising at least one substantially flat plate of non-metallic resistance material which is adapted to be disposed within said tubular means in close proximity to the inner walls thereof, said heater means, upon the occurrence of predetermined conditions, causing suillcient local heating of the adjacent portion of said tubular means to break said tubular means, thereby permitting at least one of said conducting means to be moved by said biasing means to cause the opening of the circuit controlled by said interrupter.

10. In a circuit interrupter, a tubular means at least partially of insulating material, metallic conducting means supported at either end of said tubular means, means biasing at least one oi said metallic conducting means away from the other of said conducting means, a fusible means restraining said conducting means against said biasing means, and current carrying heater means for causing said fusible means to release said conducting means upon the occurrence of predetermined conditions, thereby permitting said biasing means to cause the opening of the circuit controlled by said interrupter, said heater means comprising at least one substan tially flat plate of non-metallic resistance material disposed adjacent said fusible means.

11. In a circuit interrupter, a tubular means at least partially of insulating material, metallic conducting means supported at either end of said tubular means, means biasing at least one of said metallic conducting means away from the other of said conducting means, a fusible means for restraining said conducting means against said biasing means, and current carrying heater means for causing said fusible means to release said conducting means upon the occurrence of predetermined conditions thereby permitting said biasing means to cause the opening of the circuit controlled by said interrupter, said heater means including a current-carrying resistance means disposed adjacent said fusible means and a current carrying fusible element electrically connected in parallel with said resistance means.

12. In a circuit interrupter, a tubular means of insulating material, metallic conducting means afllxed to one end of said tubular means, said conducting means including a single, unitary clamp means-for engaging one of the conductors of a transmission line so as to electrically connect said conducting means to said conductor and to entirely support said interrupter on said conductor, a second conducting means supported at the other end of said tube, means biasing, said second conducting means away from said first conducting means, fusible means within said tubular means for completing the electrical circuit between said conducting means disposed at either end thereof, said fusible means acting upon the occurrence of predetermined conditions to permit said biasing means to move said second conducting means away from said first conducting means, thereby opening the circuit controlled by said interrupter and causing the arc incident thereto to be established within said tubular means, and means, capable of liberating gas when placed in proximity to an electric arc, disposed within said tubular means for aiding in the extinction of said are during each circuit opening operation.

13. In a circuit interrupter, a tubular means of insulating material, metallic conducting means afllxed to one end of said tubular means, said conducting means including a single, unitary clamp means for engaging one of the conductors 01 a transmission line so as to electrically connect said conducting means to said conductor and to entirely support said interrupter on said conductor, a fusible current-carrying means at 75 0,071,158 leastpartiallywithinsaidtubulsrmeansand- 1 electrically connected to said conducting means.

a second conducting means supported on the other end of said tube through the agency of said fusible means. said second conducting means including a flexible conductor for wnnecting said interrupter to the controlled equipment, the weight of said vflexible conductor biasing said secondconduciingmeansawayfromsaidtubular means, said fusible means electrically connecting said two conducting means. restraining said secondconductingmeansagainstmowementasa jrelultofthebiasingactionoftheweightofsaid flexible conductor. and being adapted to release saidsecondconducting mupontheoccurrenceofpredeterminedcoiiditioustocausethe w. and means capable of; liberating gas v, placedinproximitytoan'electricarcdisposed within said tubular means for creating l pressure therein whichaid's inmovingsaid se'cpiidconducting means to the open circuit "mum during eachgircuit opening operation.

14. In electrical apparatuaa fusible element iorcausinsoperationofsaidspparatuaand heater means for said fusible element comprising a current-carrying member of non-metallic resistance material and a second fusible element normally connected electrically in parallel with said member. V v

155 In electrical a fusible element for causing operation of said apparatus, and heater means for said fusible element. comprising a current-carrying member, of a material composed largely of carbon. forheating said element,

and a second fusible element normally colmected in parallel with said cm'rent-carrying member. e 16. In electricaltl llaram. a We element for" causing the operation of said apparatus. and

heater means forsaidfusible elementcomprising a current-carrying member-rot a material comlargely of silicon carbide, for heatingsaid einent, and a second fusible element normally inparallel with said current-carryins 17. In a circuit inter upter. a tubular-means of material havim conducting means ration'of said conducting means.

no. In acircuit interrupter. a tubular means -tially closed chamber, heat m means withinsaidchamberiorcreatingpressuretherein, andelectro-responsiv'eheatermeansqierable upon the occurrence of predetermined conditionstocausesaidheatresponsivemeanstogeneraiesuflcientpressur'ewithinsaidchanberto dectthei'iiptllrcoisaidtubularmansadlacent of the circuit by said intersaid portion of reduced cross-sectional area, the nature of said tubular means allowing the pressure within the chamber to aid in eilecting the separation of said conducting means at high speed, said heat responsive means being of a material which evolves an arc extinguishing gas when heated in order that the are which is stablished incident to the opening oi. the electrical circuit through said interrupter shall be sub- Jected to a blast of arc extinguishing gas upon the rupture of said tubular means.

19. In electrical apparatus, thermally responsive means operable when heated to eilect the actuation of said apparatus, and a current-carrying heater means for said thermally responsive means. comprising a solid member of non-metallic. resistance material an electro-responsive unit electrically connected in parallel therewith. said electro-responsive unit being operable upon the occurrence oi predetermined condition to so change the normal division of current flow between said parallel paths that a substantially greater than normal portion of the current flows through said member of resistance material.

20. In electrical apparatus, thermally responsive means operable when heated to elect the actuation of said apparatus. and heating means for said thermally responsive means. comprising a solid member of non-metallic resistance ma- -terial and an electro-responsive unit electrically connected in parallel therewith. said elactro-responsive unit being operable upon the occurrence of predetermined conditions to cause substantially allof thacurrent flowing through said heater means to how through said member of resistance material.

21 In electrical apparatus, a thermally responsive means operable when heated a predetermined amount to effect the actuation of said apparatus, and current-carrying heating means for said thermally responsive means, comprising a solid member of non-metallic resistance material and a fusible element electrically connected in parallel therewith, said element being fusible upon the occurrence of predeter-.-

minedconditionstocausesubstantisllyalloi'the current flowing through said heater means to ,flowthroughsaidresistancememherinwderto maximise the heating eilect thereof.

22. In a gas blast circuit interrupter. a tubular means of insulating material for defining the walls of an arc chamber. metallic conducting means aiiiaed to one end of said tubular means. said conducting means including a single. unitary clamp for engaging one of the conductors of a transmissionlinesoastoelectrieallyconnect said conducting means to that. conductor and to entirely support said interrupter in a generally vertical position thereon, a second conducting means supported at the other end of said tube. fusible means disposed within said are chamber for completing the electrical circuit between said conducting means, said fusible means being automatically operable upon the occurrence of predetermined conditions to open the electrical circuit through said interrupter and to establish the arc incident thereto within said arc chamber. and means for causing a blast of arc extinguishing gas to flow expulsively Z-hrough said are chamber during each operation of said interrupter in order to eflect the extinction of said are. at least one end of said are chamber being open at least during each operation of said interrupter.

28. In a gas blast circuit interrupter; a tubular means of insulating material for defining the walls of an arc chamber; a metallic conducting means afiixed to the upper end of said tubular means; said conducting means being adapted to close the upper end of the chamber defined by said tubular means and including a single, unitary clamp for engaging one of the conductors of a transmission line so as to electrically connect said conducting means to that conductor and to entirely support said interrupter in a generally vertical position thereon; a second conducting means supported at the other end of said tube, which end is open at least during each operation of said interrupter; conducting means disposed within said are chamber for completing the electrical circuit between said conducting means positioned at either end of said tubular means which defines the walls of said chamber; said conducting means including a fusible element, means of conducting material movable upon the fusion of said element to open the electrical circuit through said interrupter and to establish the arc incident thereto within said are passage, and means biasing said conducting means to the open circuit position; and means for causing a blast of arc extinguishing gas to flow expulsively through said are chamber during each operation of said interrupter to efi'ect the extinction of said arc.

24. In a circuit interrupter, conducting means movable from a closed circuit position where it completes the electrical circuit through the circuit interrupterto an open circuit position to open the electrical circuit, means biasing said movable conducting means to the open circuit position, a fusible portion in said electrical circuit for normally retaining said movable conducting means in said closed circuit position against the force exerted by said biasing means, said fusible portion when melted causing the electrical circuit to be interrupted and the arc to be drawn at the point where it melts, and current carrying heater means comprising one or more substantially fiat plates of carbonaceous resistance material having'a fixed resistance, thermally conductively Joined to said fusible portion for effecting the operation of said interrupter upon the occurrence of predetermined conditions.

25. In a circuit interrupter, conducting means movable from a closed circuit position where it completes the electrical circuit through the circuit interrupter to an open circuit position to open the electrical circuit through said interrupter, means biasing said movable conducting means to the open circuit position, a fusible portion in said electrical circuit for normally retaining said movable conducting means in said closed circuit position against said biasing means, said fusible portion when melted causing the electrical circuit to be interrupted and the arc to be drawn at the point where it melts, current carrying heater means comprising one or more substantially flat plates of resistance material having a fixed resistance, thermally conductively joined to said fusible portion for effecting the operation of said interrupter upon the occurrence of predetermined conditions, and means for electrically connecting said heater means into current responsive relationship with the electrical circuit through said interrupter, said conducting means being so arranged that the electrical current flows through said plate in a direction substantially coinciding with its least dimension.

26. In an expulsion circuit interrupter, a tubular member of insulating material, conducting means mounted on said tubular member of insulating material adjacent one end thereof, a line conductor for supporting the circuit interrupter, said conducting means adjacent one end of the tubular member including a readily detachable clamp for making electrical connection to said line conductor and suspending said tubular member therefrom in a generally vertical position, a second conducting means at the other end of said tubular member, fusible means disposed within said tubular member for completing the electrical circuit between said conducting means, said fusible means being automatically operable upon the occurrence of predetermined conditions to cause opening of the electrical circuit through the interrupter and to establish the arc incident thereto with at least one end of the arc within said tubular member, oneend of said tubular member being open during the operation of the circuit interrupter, and the interior of said tubular member having means for evolving gas when acted upon by the arc to cause an expulsive flow of gas out said open end of the tubular member to aid in extinguishing the arc.

27. In an expulsion circuit interrupter, a tubular member of insulating material, conducting means mounted on the end of said tubular member of insulating material, said conducting means closing one end of said tubular member and including a screw-operated clamp readily engageable with and disengageable from a line conductor, said clamp electrically connecting said conducting means to the line conductor andholding said tubular member suspended from the line conductor in a generally vertical position and being the sole support for said tubular member, a

second conducting means at the other end of said tubular member, a fusible portion disposed within said tubular member for completing the electrical circuit between said conducting means at the ends of the tubular member, said fusible portion causing the opening of the circuit interrupter upon the occurrence of an overload current and establishing the arc incident thereto with at least one end in said tubular member, means biasing the melted parts of said fusible portion to separate and lengthen the arc, and the interior of said tubular member including means which when acted upon by the arc gives ofl gas to flow expulsively out the open end of said tubular member and aid in extinguishing the are.

28. In an expulsion circuit interrupter, a tubular member of insulating material, conducting means mounted on saidtubular member of insulating material adiacent one end thereof, a line conductor for supporting the circuit interrupter, said conducting means adjacent one end of the tubular member including a readily detachable clamp for making electrical connection to said line conductor and suspending said tubular member therefrom in a generally vertical position, a second conducting means at the other end of said tubular member, a second line conductor connected to said second conducting means, fusible means disposed within said tubular member for completing the electrical circuit between said conducting means, said fusible means being automatically operable upon the occurrence of predetermined conditions to cause opening of the electrical circuit through the interrupter and to establish the arc incident thereto with at least one end of the are within said tubular member,

one end of said tubular member being open during the operation of the circuit interrupter, and the interior of said tubular member having means for evolving gas when acted upon by the arc to cause an expulsive flow of gas out said open end of the tubular member to aid in extinguishing the arc, and said operation of the circuit interrupter causing said second line conductor to be disconnected from said tubular member of insulating material thereby relieving said tubular member of the voltage between said line conductors.

29. In a high tension expulsion circuit interrupter, a tubular member of insulating material, conducting means mounted on said tubular member of insulating material adjacent one end thereof, a line conductor for supporting the circuit interrupter. said conducting means adjacent one end oi the tubular member closing said end of the tubular member and including a readily detachable clamp for mahng electrical connection to said line conductor and suspending said tubular member therefrom in a generally vertical position. said readily detachable clamp securely fastening the circuit interrupter in place on the line conductor and holding it there during the expulsion action of the interrupter, a second conducting means at the other end of said tubular member, fusible means disposed within said tubular member for completing the electrical circuit between said conducting means. said fusible means being automatically operable upon the occurrence of predetermined conditions to cause opening of the electrical circuit through the interrupter and to establish the arc incident thereto with at least one end of the are within said tubular member, the other end oi said tubular member being open during the operation of the circuit interrupter, and the interior 01' said tubular member having means for evolving gas when acted upon by the arc to cause an expulsive flow of gas out said open end of the tubular member to aid in extinguishing the arc.

EDWARD I". BECK. 

